There is no “canned” command to do what you are describing. You could certainly create a command where the CPP (be it in CL or RPG) provides the application level function you generally describe.
It’s just a stab, but maybe you could build on this:
what about a physical file with your URL or URL template.
The file could be defined with one field, multiple fields, subdivided fields.
In your CL
RCVF DEV(*FILE) /* READ A RECORD*/
Then refer to the field names as &variables to manipulate or use in cmds.
I don’t get to work with URLs, so maybe I’m way off base.